This invention relates generally to the molding of articles of manufacture, and relates more particularly to the molding of golf club heads composed of metal or other materials. The invention has particular utility in the molding of golf club heads composed of wax, as patterns or master models for use in the so-called "lost wax" process of molding, also called "investment casting". The terms molding and casting are interchangeable for the purposes of this invention.
A golf club comprises, in general, a head that may be composed of wood, metal or other suitable material, including plastic, and an elongated handle formed by a shaft that is connected at one end to the head and has a grip at the other end. The shaft typically is attached to the head in a bore formed in a tubular neck or ferrule that projects upwardly at a selected angle relative to the head and relative to the hitting surface or "face" of the club. The connection between the head and the shaft sometimes is referred to as the "hosel".
The basic types of clubs are "woods" and "irons", terms derived from the traditional materials that were used in the construction of their heads, and putters, for shots on the greens. The so-called woods are the driver and the fairway clubs having relatively large, thick heads. A relatively recent development in this area is the so-called "metalwood", in which the head has the shape of a traditional wood but formed of metal, molded in hollow form and often filled with plastic for "feel" and sound-deadening purposes. Examples of metalwoods are shown in U.S. Pat. Nos. 4,214,754 and 4,417,731.
The so-called irons have blade-like metal heads, which may be composed of steel or aluminum and usually are substantially solid. The irons have faces that are tilted at different "loft" angles in the normal hitting attitude of the head, and generally are used for shorter shots or more difficult "lies", for example, when the ball is in longer grass, in sand, or otherwise affected by its surroundings. Examples of irons are shown in U.S. Pat. Nos. 2,931,098 and 4,630,825. Putters, regarded as another class of clubs, have heads with faces that are substantially vertical in the normal hitting attitude of the club head.
The dynamics of golf, between the swinging club and the golf ball that is stationary until the impact of the high-speed club head, are much more complex than might be thought by a person unfamiliar with golf club design. The normal back stroke commences with the underside or "sole" of the club substantially flat on the ground, and the face of the club behind the ball and inclined upwardly and rearwardly at a loft angle, between the face and an imaginary vertical plane, that depends upon the particular club. For example, the usual loft angle of a number "5" iron is between thirty and thirty-four degrees, and the usual loft angle of a number "1" wood, or driver, is eight to twelve degrees. For a putter, there is no significant incline.
Another important angle in golf club heads is the angle between the shaft and the club head, called the "lie angle". When the underside of the club is on the ground in the proper hitting attitude, the lie angle is the angle at which the handle is inclined upwardly from the ground toward the golfer, and is established by the angle of the neck or hosel relative to the club head. Standard lie angles or ranges of such angles are prescribed for different clubs, with prescribed variations for mens' and womens' clubs and for variations from standard lengths of shafts. For example, a standard lie angle for mens' drivers of standard length (i.e., 43 inches) is fifty-five degrees, with standard variations in the range of fifty-one degrees to fifty-seven degrees. For a standard mens' "2" iron (39 inches long), the standard is fifty-six degrees and the range is fifty-two degrees to fifty-eight degrees. Standard variations provide so-called "flat" or "upright" lies, according to the preference of particular golfers, and such preferences may vary with a golfer's size, stance or stroke. Shaft flex during the stroke also affects the actual lie angle at the moment of impact.
The so-called "face angle" of a wood is the angle of the face of the club head relative to the intended direction of flight of the ball, and may be "square" or "straight" (ninety degrees to the line of flight) or slightly off "square" in either direction for an "open" or a "closed" face. Also, irons have either "bounce" or "scoop" sole angles, which correspond to the face angles of woods. These also are variables in the design of golf clubs.
In custom-made clubs, lie angles and other angles can be adapted to the preference of the customer, but with a significant increase in cost over the cost of mass-produced clubs. Such variations have been accomplished by providing different molds to produce club heads with hosels disposed at the various angles relative to the bodies of the clubs, or by producing club heads with standard angles and then bending the hosels to "personalize" the clubs. Such bending of hosels in metalwoods is mentioned in Pat. No. 4,214,754 as an adjustment for both loft and lie angles. A more detailed description of bending procedures and equipment is contained in "Golf Club Design, Fitting, Alteration and Repair", published by Ralph Maltby Enterprises, Inc. (2d. Ed. 1982).
The bending of club heads to vary loft and lie angles avoids the expense of providing separate tooling for producing each variation, but has a number of disadvantages. Bending inherently lacks precision and can weaken the metal or other material that is bent, so there is a serious risk of breakage, either during the bending process or later during use of the club. The time and equipment required add to the cost of the clubs, and considerable skill is required to achieve optimum results. Finally, the bending of a hosel to change any angle in the club head may inadvertently affect other angles in a manner that significantly affects the performance of the club.
As a practical matter, manufacturers have chosen either to produce a given mass-produced club with standard preselected angles, including a single lie angle, or to provide the standard club with a limited number of different lie angles, typically three, produced from three sets of molds, or from one basic mold and different mold inserts for adapting the basic mold to form hosels at the different angles. Variations from the standard clubs so provided are left to the "custom" market or to the bending of standard clubs.
The present invention provides a novel molding method and apparatus for selectively varying the angles of the shaft relative to the club body as a part of the molding of the club head or the pattern or master for the club head.